This invention relates generally to novel para-tertiary alkyl phenyl substituted triazines and pyrimidines and their use as protectants against degradation by environmental forces, including ultraviolet light, actinic radiation, oxygen, moisture, atmospheric pollutants and combinations thereof.
Exposure to sunlight and other sources of ultraviolet radiation is known to cause degradation of a variety of materials, especially polymeric materials. For example, polymeric materials such as plastics often discolor and may become brittle as a result of exposure to ultraviolet light. Accordingly, a large body of art has been developed directed towards materials such as ultraviolet light absorbers and stabilizers which are capable of inhibiting such degradation.
A class of materials known to be ultraviolet light absorbers are o-hydroxyphenyltriazines, in which at least one substituent on the 1, 3 or 5 carbon on the triazine ring is a phenyl group with a hydroxyl group ortho to the point of attachment to the triazine ring. In general this class of materials is well known in the art. Disclosures of such compounds can be found in U.S. Pat. No. 3,242,175 and U.S. Pat. No. 3,244,708.
A further example is found in U.S. Pat. Nos. 3,843,371 and 3,896,125, which disclose various hydroxyphenyltriazines. These triazines show poor solubilities and poor stabilities, and can discolor with time.
Hydroxyphenyltriazines in combination with other UV absorbers such as hydroxyphenylbenzotriazoles, benzophenones, oxanilides, cyanoacrylates, salicylates, acrylonitriles and thiozlines, are also well known. For example, U.S. Pat. Nos. 4,853,471, 4,973,702, 4,921,966 and 4,973,701 disclose such combinations.
Typically, the aforementioned aryl ring with the hydroxyl group ortho to the point of attachment to the triazine ring is based on resorcinol and, consequently, this aryl ring also contains a second substituent (either a hydroxyl group or a derivative thereof) para- to the point of attachment to the triazine ring. For example, U.S. Pat. Nos. 3,118,837 and 3,244,708 disclose p-alkoxy-o-hydroxyphenyl triazines with improved UV protection, but such triazines also exhibit poor solubility and poor long-term stabilities.
This para-substituent can be "non-reactive," as in the case of an alkyloxy group, or "reactive" as in the case of a hydroxyalkyloxy (active hydrogen reactive site) or (meth)acryloyl (ethylenic unsaturation reactive site) group. For the purposes of the present invention, the former are referred to as "non-bondable" benzocycle-substituted pyrimidines and triazines and the latter are referred to as "bondable" para-tertiary alkyl phenyl substituted pyrimidines and triazines.
Many polymer additives (such as ultraviolet light stabilizers) volatilize or migrate out of the polymer substrate to be protected, or are adsorbed (chemically or physically) by one or more systems components (such as pigments), thereby diminishing their effectiveness. Such volatilization, migration and adsorption problems are examples of the general problems of lack of solubility and compatibility found for many commercial polymer additives. Bondable triazines are well known in the art. For example, U.S. Pat. Nos. 3,423,360, 4,962,142 and 5,189,084 disclose various bondable and the incorporation of these compounds into polymers by chemical bonding. Bondable stabilizers have a potential advantage in this respect in that, depending on the bondable functionality and the particular polymer system to be stabilized, they can be chemically incorporated into a polymer structure via reaction of the bondable functionality either during polymer formation (such as in the case of polymerizing monomers or a crosslinking polymer system) or subsequently with a preformed polymer having appropriate reactive functionality. Due to such bonding, migration of these UV absorbers between layers of multi-layer coatings and into polymer substrates is greatly reduced.
Several of the previously incorporated references disclose tertiary alkylated substituted triazines. For example U.S. Pat. No. 3,242,175 and U.S. Pat. No. 3,244,708 disclose mono-tertiary butylated benzene triazines. There remains a need for new UV-stabilizers which possess improved compatibility with the polymer systems to which they are added, as well as impart improved environmental stability to such systems. The present invention provides novel para-tertiary alkyl phenyl substituted triazine and pyrimidine stabilizers which satisfy this need.